Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 804	$ 629	$ 1,558	$ 892
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	(614)	285	(331)	(166)
Realized and unrealized gains (losses) on derivatives	1	(9)	(10)	(13)
Realized and unrealized gains (losses) on marketable securities	0	(3)	(2)	6
Other comprehensive income (loss)	(613)	273	(343)	(173)
Total comprehensive income	191	902	1,215	719
Comprehensive income attributable to noncontrolling interests	22	89	159	140
Comprehensive income attributable to Johnson Controls	$ 169	$ 813	$ 1,056	$ 579